This Part 2-9 of IEC 61558 applies to stationary or portable single-phase air-cooled (natural or forced) associated safety isolating transformers for class III handlamps for tungsten filament lamps, having a rated supply voltage not exceeding 1 000 V a.c., a rated frequency not exceeding 500 Hz and a rated output not exceeding 10 kVA. It has the status of a group safety publication in accordance with IEC Guide 104